Sewage-treatment plant



Dec. 7 1926.

M.`PRSS SEWAGE TREATMENT PLANT Filed June 11 1925 2 Sheets-Sheet 1 Dec. 7 1926. 1,609,830

M. PRUss sEwAGE TREATMENT PLANT Filed June 11 1925 2 Sheets-She-et `2 si 1|* ll e il E w- ,N

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T/Wfhesses: Jn Veni-on ?atented Dec. 7, 1926.

UNITED .STATES c 1,609,830 PATENT OFFICE.

Max rRss, F ESSEN, GERMANY.

@WAGE-TREATMENT' PLANT.

Application led .Tune 11, 1925, Serial No..36,441, and in Germany -June 19, 1824.

For ,its, quick digestion, the sludge in sludge digestiongchambers of sewage treatment plants must be kept warm and f requently agitated.k With the two-storied sewage treatment plants such as Imhoii' tanks and similar constructions, in which the fresh-sludge flows lfrom the settlin basins through slots into ythe vdigestion c ambers underneath, the digestion chambers are kept lo favourably warm by the sewage lowmg above the same andthe sinking fresh-sludge is well mixed with already digested sludge. A drawback of such plants lies, however, in the fact that an artificial agitation of the )5 contents ofthe digestion chamber, by which an increased gas generation and a quick sludge digestion` is attained, is not possible by reason of its slot connection with the settling basin, while furthermore the slots, by disturbances in "they digestion chamber orl by careless attendance to the plant, cause easily a return of digested sludge or water from the digestion chamber into the settling basin. Therefore, attempts have been made to' further treat the fresh-sludge in digestion chambers located separate from the settling basins, the result being however unsatisfactory, because the required digestion chambers must be built much larger than in 30 two-storied plants. h e

In the improved plant forming the subject' matter of the present invention, the advan tages of the two-storied sewage treatment plants and of the hitherto known plants with separate sludge digestion are combined. In the accompanyingdrawings: Fig. 1 is across-section through settling basins and sludge digestion chamber of a sewage treatment plant, and Fig. 2 is a longitudinal section' through one of the settling basins, while Fig. 3 is asimilar view to Fig. 1 showing a modification of the cross-section through the plant. i Y y' Settling basins 1 and juxtaposed digestion chamber 2 are so combinedin oneconstruc- .tion that they are separated from one anotherby thin walls 3 of heat-permeable material only, so that the heating of the -digestion chamber by the settling basins remains as favourablel las with the two-storiedV plants mentioned. vThe fresh-sludge in this arrangement must be raised artificially from the settling basins intothe digestion chamber, whereby the. height of the sludge level in the digestion chamber is ,independent of the Water level in the settling basins. The

digestion chamber can thus be built as high as convenient, whereby with rocky ground ory with high underground water the cost of deeply extending sludge tanks is reduced. lVith the improved arrangement care must be taken that the boundary Walls of the digestion chamber extending above the settling basins are well insulated against heat radia-v tion, e. g. by an insulating envelope 4 shown 65 in Figs. 1 an'd3, and that, furthermore, when agitating the contents of the digestion chamber, the sludge in motion is continuously brought in' contact with the heating walls 3 ofthe settling basins. 70

Referring 'to Fig. 3, the sludgeflows down the shallow bottom 5 to the perforated pipes (Sthrough which digestionk gases `from the gas collector 7 are, after their passage through a compressor, forced into the sludge in a way known in the art. By said gas supply the sludge is caused to ascend along the heatingwalls 3 and after liberation of the gases to drop again at the middle of the digestion chamber. By the arrangement of guiding-walls 8 in the latter a short distance from the heating walls 3 and extending from the lower ends of the latter into the top part of said chamber, said artificial agitation can be increased. y By heating the digestion gases priorto their supply to the pipes 6, a further increased heating of the digestion chamber can be obtained, this being known in the art. If the digestion chamber is used without articial agitation, a natural agitation takes place with the aid of the inclined guiding-walls 8, because the sludge enriched by digetion gases ascends from the bottom of the digestion chamber'along the guiding-walls 8 and extends over the whole 95 sludge level in order to drop again after i liberati n 'of its gases; the larger portion of the sinking sludge passing through the space between Athe guiding-walls 8 and the heating Walls 3. 100 In order to .easily raise the fresh-sludge settled 'in the settling basins, from the. latter into the digestion chamber', it is collected in a shallow fresh-sludge channel 9, or in adeep fresh-sludge channel 9, at the bot- 105 tom of the settling basin, to which it Hows down along the steep side walls of the latter. Through said channel, which is narrow comparatively tothe width of the basin, a sludge-pipe 11 is dragged by movable means, for instance a truck 10 running on rails above the basin, said pipe carrying behind its lower orifice a shovel 12 occupying the whole cross-section of said channel. Said shovel 12 serves, when removing the sludfe by means of the pipe 11, to revent an admission of water from the a ready emptied part of the channel lto said pipe and thus a.

dilution of the slud e. The'. edges of lthe shovel are fitted with mdia rubber prthe like,

.so as to tightly itthe Walls ofthe channel 9 whereb at each pasage .ofthe shovel through tliY l channel 9. the' walls of tbe latter are thoroughly cleaned from fresh-sludge. This is very important 'forkeepingthe water in the basin fresh,`as'a .long storage of freshsludge in the sludge channel results in `la;

n rising of saidv sludge and insa soilingof the settling basin. The raising of 4the fresh-` sludge thron h 'thepipe'llfcan1-be eiiectedby any suita lesludge raisin contrivances. In order, however, to keep t e truck` so lightA that it can be easily advanced by hand, it is preferable'tc usethe compressed-air plant ilustrated, consisting ofa compressedair supplypjpe .15 extending over-the whole n 'i the basinl 1n and ,lievi/ugr, several closable branches, lt'tmeach soi ywhich a.

pipe' 13 von the .10' leading intothebottomend of the sludge pi, e llfcan .be connected by means of a flexi le .pipe vlilou the upper end ot said pipe 13, 'so that during the whole advance of the truck 10 alongthe settling `basin compressed-air can be su plied to the sludge pipe 1l whereby t e sludge is raised therein. .Y

The pipe 11 does not lead the'fresh-sludge directly into the digestion chamber but to. an intermediary tter, 16, which can take-up the whole sin ge contents of a. ,basin in a short time and gradually. deliver thesame by gravity iiow, as indicated at 17, into the digestion chamber, so that the mixing lof the fresh-sludge with digest-ed sludge remains digestion chamber and cannotzbe` kept away yfrom the latter in thev yconventional twostoried plants. Such noxious" sludge can,

after its inspectionin the gutter` 16, -be directly led onto. the sludge drying place, so

- that it doesnot come'in contact with `the contents in the di estion chamber.

The, freshslu ge is removed from tht channel 9 into the gutter 16 as often' as this isrequired for'keeping the sewage clean. Generally, a removal on every second or third day will suiiice. A rising of the sludge hardly occurs with domestic sewage. In case that a less frequent removal is desired or the lsludge has a llght buoyancy, that part of the settllng basin lying above the sludge channel 9 must be separated from the remaining parts by means of perpendicular straight partition-wallsv 18, or bent partitionwalls 18*,extending over thel who e length of the settling basin. The sludge slipping down the steep walls of the settling basin passes through slots 19in' the lower ends of said Ipartition-walls into the fresh-sludge channel 9. At normal working of the plant,

the sewage 'flows throu h the whole crossv section fof the settling. asin, while during the iremoval of the sludge from the channel 9 or upon risin of the fresh-sludgev owing to lretarded Asluv e removal, the to and oli'- iiowof the midd e part of the settling basin between the artitien-'walls 18 must be shutofso that t e whole sewage is temporarily treated in the outer and inner parts only of the settling basin between the wallsof the latter and the partition-.walls 18 and remains thus, uninuenced bythe rising sludge. At

normaliworkingof the plant, said partition-A walls 18a-How further to fully utilize the lowermost parts of the cross-section` in the settling basin for the treatmento With a mere horizontal iiowing o' domestic sewage through the settling basin, an effective treatment depth of 11% to 2 meters only can be taken into account. By the required steep inclination of the side walls of the settling basin down to the middle sludge channel 9, the middle part of the settling basin becomes essentially deeper than 2 meters. The

yliquid 'level 'in said middle part between the'partition-walls 18 can be kept at different height to that in the lateral parts of the settling basin, whereby, beside the longitudinally directed current in the settiing basin, transversely directed up and down moving currents are created between the three" parts in the settling basin, which make the whole cross-section down to the slots 19 effective for the treatment. The difference of the liquid level between the middle part and the two cuter parts in the setthng basin can, for instance, be attained by a gutter 20 extending into the upper part of the settlin basin and leading to the outlet thereof an causing, in spite of the slots 19, a slight smkingjof the level of the longitudinally directed water current in the middle part by fm'eans of a plurality of adjustable slides-21communicat1ng between sald middle part and said utter 20, while further- 'more-inthis case t e overliow at 22 (Fig.

2) from said middle part is located somefwha't dee er than that from the two outer parts of t e settling basin.

The improved combined arrangement of settlmg basin and digestion chamber wth theiraccessories can also be used in connec` tion with circular plants having a central digestion chamber and a concentric outer settling basin; the illustrations in Figs. 1 and 3 being then central cross-sections through the circular plant.

What I claim, is

l. In a sewage treatment plant, the com-F bination of a settling basin and a juxtaposed digestion chamber separated from one another by thin walls of heat-permeable material, free upwardly projecting insulated walls enclosing the top part of said chamber and extending above said basin, means to artificially agitate the contents of said chamber, and sludge guiding-walls in said chamber spaced a short distance from said thin walls and extending from the lower ends of the latter into the top part of said chamber.

2. In a sewagetreatment plant as s eciied in claim l, a narrow fresh-sludge c annel at the bottom of the settling basin, an intermediary fresh-sludge gutter at theouter top end of the digestion chamber in comvmunication with the interior of the latter,

a movable sludge-pipe extending from said channel to above said gutter,-a cleaning shovel tightly fitting the 'walls of said channel and attached to said pipe behind the lower orifice thereof, means to raise the sludge from said channel through said pipe into said gutter, and movable means above 'said settling basin carrying said pipe and `adapted to drag the latter with said shovel through said channel.

nel at the bottom of the settling basin, and

perpendicular partition-walls with slotted lower ends in the latter separating the middle part above said channel from the two outer parts of the settling basin.

4. In a sewage treatment planty as specified in claim 1, a narrow fresh-sludge channel at the bottom of the settling basin, perpendicular partition-walls with slotted lower ends in the latter separating the middle part above said channel from the two outer parts of the settling basin, and means to keep the sewage current in said middle part at different level to that in the two outer parts.

5. In a sewage treatment plant as specified in claim l, a narrow fresh-sludge channel at the bottom of the settling basin, per; pendicular partition-walls with slotted lower ends in the latter separating the middle part above said channel from the two outer parts of the settling basin, a gut-ter eXtend ing into the upper part of the settling basin and leading to the outlet thereof, and a plurality of adjustable slides communicating between said middle part and said gutter, the overflow from the middle part being located deeper than that from the two outer parts of the settling basin.

In testimony whereof I have hereunto set my hand.

MAX PRSS. 

